Thermoplastic olefin resin composition and laminated film or sheet thereof

ABSTRACT

A thermoplastic olefin resin composition composed of a blend of 
     (i) 5 to 95% by weight, based on the weight of the blend, of a random copolymer consisting essentially of 55 to 85 mole% of propylene and 45 to 15 mole% of 1-butene and having a heat of fusion of 10 to 80 joules/g determined by differential thermal analysis using a differential scanning calorimeter, and 
     (ii) 5 to 95% by weight, based on the weight of the blend, of an isotactic propylene resin containing 0 to 10 mole% of another α-olefin and having a melting point of 135° to 165° C. and a melt index, measured at 230° C., of 0.1 to 20; and a laminated olefin resin film or sheet thereof.

This invention relates to a thermoplastic olefin resin compositioncomposed of a blend of (i) a random copolymer consisting essentially ofpropylene and 1-butene and (ii) an isotactic propylene resin having amelting point of 135° to 165° C. and a melt index (at 230° C.) of 0.1 to20. The invention also relates to a laminated film or sheet having alaminated layer of the thermoplastic olefin resin composition. Itfurther relates to the thermoplastic olefin resin composition in theform of a melt-shaped article.

When the resin composition of this invention comprises a majorproportion of the random copolymer (i) of propylene and 1-butene, it hasmarkedly improved antiblocking property and mechanical strength inaddition to various other desirable properties such as superiortransparency, superior low-temperature heat sealability and good lowtemperature shrinkability. Because of these improved properties, thisresin composition is very useful as melt-shaped articles such asshrinkable packaging films or sheets, protective films or sheets,textile packaging films or sheets, and other general-purpose packagingfilms.

When the resin composition comprises a major proportion of the isotacticpropylene resin (ii), it has remarkably improved transparency,resistance to whitening by impact and resistance to whitening by bendingin addition to other desirable properties such as superior thermalstability, superior mechanical strength and hinge characteristics.Because of these improved properties, the resin composition is veryuseful as melt-shaped articles, for example various containers such ascontainers for edible oils and seasonings, containers for transportingliquids and containers for liquid detergents; vacuum-formed packs suchas blister packs and skin packs; tapes having superior opticalcharacteristics, general-purpose packaging films and sheets, andshrinkable packaging films and sheets; battery cases, toys and otherinjection-molded articles having superior resistance to whitening byimpact; and book covers and files having superior resistance towhitening by bending.

A random copolymer consisting essentially of propylene and 1-butene andan isotactic propylene resin have heretofore been known. Laminated orcomposite films or sheets prepared by laminating a copolymer ofpropylene and 1-butene onto a polypropylene film are also known (Britishpatent specification No. 1,452,424 published on 13th Oct. 1976).

According to the technique suggested by British patent specification No.1,452,424, a layer of a copolymer consisting essentially of 80 to 95% byweight (84.3 to 96.2 mole%) of propylene and 5 to 20% by weight of1-butene is laminated on a polypropylene film. The British Patent statesthat the copolymer can be produced by the method disclosed in BritishPat. No. 1,084,953. The British Pat. No. 1,084,953 discloses a copolymerconsisting essentially of 5 to 50% by weight (6.5 to 57.2 mole%) ofpropylene and 50 to 90% by weight of 1-butene. However, this prior artreference does not at all disclose a blend of the copolymer and anotherresin, especially a propylene resin.

If an attempt is made to improve the low-temperature heat sealabilityand the shrinkability of a film or sheet of a random copolymer ofpropylene and 1-butene, the product inevitably has poor antiblockingproperty and poor scratch resistance. The present inventors haveundertaken extensive work to remove this incompatibility. The work ledto the discovery that a superior thermoplastic olefin resin compositionhaving all these properties without incompatibility can be obtained byblending (i) a random copolymer consisting essentially of 55 to 85mole%, preferably 60 to 82 mole% of propylene and 45 to 15 mole%,preferably 40 to 18 mole% of 1-butene and having a heat of fusion of 10to 80 joules/g, preferably 20 to 70 joules/g, determined by differentialthermal analysis using a differential scanning calorimeter (DSC) with(ii) an isotactic propylene resin which contains 0 to 10 mole% ofanother α-olefin and has a melting point of 135° to 165° C., preferably140° to 165° C., and a melt index (230° C.) of 0.1 to 20, preferably 0.5to 12, especially using the random copolymer (i) in a major proportion.It has also been found that the resin composition comprising a majorproportion of the random copolymer (i) exhibits very useful improvedeffects as melt-shaped articles such as films or sheets and also as alaminated layer on a substrate of an isotactic propylene resin.

It has also been found that by using a major proportion of (ii)isotactic propylene resin, a superior thermoplastic olefin resincomposition can be provided which eliminates the poor transparency,whitening by impact and whitening by bending which are inherentlypossessed by the propylene resin, while maintaining the variousdesirable properties of the propylene resin such as superior thermalstability, superior mechanical strength and hinge characteristics.

It is an object of this invention therefore to provide a thermoplasticolefin resin composition composed of a blend of a random copolymerconsisting essentially of propylene and 1-butene and an isotacticpropylene resin, which has these improved properties.

The above and other objects and advantages of this invention will becomemore apparent from the following description.

According to this invention, there is provided a thermoplastic olefinresin composition composed of a blend of

(i) 5 to 95% by weight, based on the weight of the blend, of a randomcopolymer consisting essentially of 55 to 85 mole%, preferably 60 to 82mole%, of propylene and 45 to 15 mole%, preferably 40 to 18 mole%, of1-butene and having a heat of fusion of 10 to 80 joules/g, preferably 20to 70 joules/g, determined by differential thermal analysis using adifferential scanning calorimeter (DSC), and

(ii) 5 to 95% by weight, based on the weight of the resin, of anisotactic propylene resin which contains up to 10 moles% of anotherα-olefin and has a melting point of 135° to 165° C., preferably 140° to165° C., and a melt index (230° C.) of 0.1 L to 20, preferably 0.5 to12.

The random copolymer (i) preferably has a melt index of 0.1 to 40.

When the thermoplastic olefin resin composition of this inventioncomprises a major proportion of the random copolymer (i), the amount ofthe random copolymer (i) is 50 to 95% by weight, preferably 55 to 90% byweight, and the amount of the isotactic propylene resin (ii) is 5 to 50%by weight, preferably 10 to 45% by weight. When the thermoplastic olefinresin composition of this invention comprises a major proportion of theisotactic propylene resin (ii), the amount of the random copolymer (i)is 5 to 50% by weight, preferably 10 to 45% by weight, and the amount ofthe isotactic propylene resin is 50 to 95% by weight, preferably 55 to90% by weight.

In the random copolymer (i) consisting essentially of propylene and1-butene, the propylene content and the melting point of the resin havea substantial correlation with each other. For example, the meltingpoint Tm(°C.) of a copolymer having a propylene content of y mole% isusually within the range of 1.4y-16≦Tm≦1.4y+24, and in many cases withinthe range 1.4y-11≦Tm≦1.4y+19. Hence, if a copolymer having a propylenecontent of more than 85 mole% is used, the transparent, low-temperatureheat sealability and low-temperature shrinkability of the resultingcomposition become poor. On the other hand, if the propylene content isless than 55 mole%, the melting point of the copolymer becomes too low,and consequently, the film undergoes blocking, or spontaneously shrinksduring storage. Furthermore, if the propylene content is too low, theuniform miscibility of the copolymer (i) with the isotactic propyleneresin (ii) becomes poor, and an adverse effect is exerted on thetransparency of the resulting composition.

For this reason, the random copolymer (i) consisting essentially ofpropylene and 1-butene used in this invention should have a propylenecontent of 55 to 85 mole %, preferably 60 to 82 mole%.

The random copolymer should have a heat of fusion of 10 to 80 joules/g,preferably 20 to 70 joules/g, determined by differential thermalanalysis using a differential scanning calorimeter (DSC). The heat offusion correlates with the degree of crystallization of the randomcopolymer resin (i). A random copolymer having a heat of fusionexceeding 80 joules/g has too low a content of 1-butene, or it is theone in which 1-butene is copolymerized to form a blocked copolymer. Ifsuch a copolymer is used, the resulting composition has poortransparency, low-temperature heat sealability and low-temperatureshrinkability. On the other hand, a random copolymer having a heat offusion of less than 10 joules/g has poor mechanical characteristics andthermal stability, and tends to undergo blocking and has a sticky feel.Even if such a resin is blended with the isotactic propylene resin (ii),the performance of the resulting composition cannot be improved to anextent feasible for practical purposes.

For this reason, the random copolymer (i) used in this invention shouldhave a heat of fusion of 10 to 80 joules/g, preferably 20 to 70joules/g.

In addition to meeting the conditions of propylene content and heat offusion described above, the random copolymer (i) has a melt index ofpreferably 0.1 to 40, more preferably 1 to 10. If the melt index is lessthan 0.1, good products are difficult to obtain in film formation. Onthe other hand, if the melt index exceeds 40, the mechanical strength ofthe resulting film tends to decrease. It is preferred, therefore, forthe random copolymer (i) to have a melt index within the above-specifiedrange.

The heat of fusion of the random copolymer (i) of this inventionconsisting essentially of propylene and 1-butene is calculated by usingas a baseline a straight line obtained by directly extrapolating to alower temperature side the specific heat curve (preferably the specificheat curve at 160° C. to 240° C.) of a sample of the copolymer in acompletely molten state which specific heat curve is determined bydifferential thermal analysis using a differential scanning calorimeter(DSC).

The melting point and heat of fusion are measured under the followingmeasuring conditions. The sample is allowed to stand at 200° C. for 5minutes, cooled to -40° C. at a rate of 10° C./min., and allowed tostand at -40° C. for 5 minutes. Then, the temperature is raised at arate of 20° C./min, and the measurement is made at a temperature of from-40° C. to 200° C.

The isotactic propylene resin (ii) to be blended with the randomcopolymer (i) in this invention may contain up to 10 mole%, preferablyup to 5 mole%, of another α-olefin such as ethylene or 1-butene. Theisotactic propylene resin (ii) should have a melting point of 135° to165° C., preferably 140° to 165° C., and a melt index, measured at 230°C., of 0.1 to 20, preferably 0.5 to 12. If the melting point of theresin (ii) is lower than 135° C. and/or its melt index exceeds 20, theolefin resin composition has low rigidity and poor mechanicalcharacteristics. Furthermore, a film prepared from the olefin resincomposition has poor slip property and undergoes blocking.

The random copolymer (i) can be obtained by random-copolymerizingpropylene and 1-butene using a catalyst prepared from (a) a solidcomplex at least containing magnesium, titanium and halogen, (b) anorganometallic compound of a metal of Groups 1 to 3 of the periodictable, preferably an organoaluminum compound, and (c) an electron donor.A part or the whole of the electron donor (c) may be fixed to a part orthe whole of the solid complex (a). Or the electron donor (c) may bepre-contacted with the organometallic compound (b) prior to use.According to an especially preferred embodiment, a part of the electrondonor (c) is fixed to the solid complex (a), and the remainder is addeddirectly to the polymerization system or pre-contacted with theorganometallic compound (b). In this case, the electron donor fixed tothe solid complex (a) may be the same as or different from the electrondonor directly added to the polymerization system or pre-contacted withthe organometallic compound (b).

The solid complex (a) can be produced by various known methods such asthose disclosed in Japanese Patent Publications Nos. 36786/77 (publishedon Sept. 17, 1977), and 36913/77 (published on Sept. 17, 1977), JapaneseLaid-Open Patent Publications Nos. 126590/75 (published on Oct. 4,1975), 28189/76 (published on Mar. 9, 1976), 92885/76 (published on Aug.14, 1976), 127185/76 (published on Nov. 5, 1976), 136625/76 (publishedon Nov. 26, 1976), and 87489/77 (published on July, 21, 1977), and WestGerman Laid-Open Patents Nos. 2643143 (published on June 2, 1977),2656055 (published on June 23, 1977) and 2708588 (published on Sept. 8,1977).

A copolymer prepared from the above monomers using a titaniumtrichloride-type catalyst without using the solid complex (a) has ahigher degree of crystallization even when itspropylene content is thesame. Since the comonomer to be introduced into the copolymer does nottake a random configuration, the copolymer has poor transparency anddoes not suit the purpose of the present invention. On the other hand, acopolymer prepared from these monomers using a vanadium-type catalystscarcely shows a heat of fusion. Since such a copolymer has poormechanical characteristics and heat distortion, it cannot be used in thepresent invention.

The method of copolymerization is well known. Propylene and 1-butene canbe copolymerized either in the liquid phase or in the gaseous phase.Preferably, the copolymerization is carried out in the liquid phaseunder conditions such that the resulting copolymer dissolves in it. Theliquid-phase copolymerization can also be performed in an inert solvent,for example an aliphatic hydrocarbon such as hexane, heptane orkerosene, an alicyclic hydrocarbon such as cyclohexane, or an aromatichydrocarbon such as benzene, toluene or xylene. Alternatively, theolefin itself may be used as a reaction medium.

In the case of the liquid-phase copolymerization, the concentration ofthe solid complex (a) in the polymerization system is preferably 0.001to 0.5 millimole as titanium atom per liter of liquid phase, and theconcentration of the organometallic compound (b) is preferably 0.1 to 50millimoles as metal atom per liter of liquid phase. The amount of theorganometallic compound (b) is chosen such that the ratio of the metalatom to the titanium atom of component (1) becomes 1:1 to 1000:1,preferably 1:1 to 200:1. The amount of the electron donor (c) is 0.001to 1 mole, preferably 0.01 to 0.9 mole, per metal atom of theorganometallic compound.

The copolymerization can be performed in the same way as in thepolymerization of an olefin with an ordinary Ziegler catalyst. Thecopolymerization temperature is usually 30° to 140° C., preferably 50°to 120° C. Preferably, the polymerization is carried out under anelevated pressure, usually from atmospheric pressure to 50 kg/cm²,preferably about 2 to 20 kg/cm². The ratio of propylene to 1-butene toproduce copolymers having a propylene content of 40 to 90 mole%, whichdiffers according to the polymerization pressure, is usually 85:15 to10:90.

The molecular weight of the copolymer can be controlled to some extentby varying the polymerization conditions such as the polymerizationtemperature and the proportions of the catalyst ingredients. Theaddition of hydrogen to the polymerization system is most effective.

All random copolymers which have propylene contents and heats of fusionand preferably melt indexes, which are specified hereinabove, can beused. Especially preferred copolymers are random copolymers consistingessentially of propylene and 1-butene which can be produced by theprocess described in detail in U.S. patent application Ser. No. 861,894covering the invention of other researchers of the Applicant's company.

The thermoplastic olefin resin composition of this invention can beshaped into various types of meltshaped articles having superiorproperties.

The random copolymer (i) used as an ingredient of the thermoplasticolefin resin composition of this invention can be used as aheat-sealable laminate film or sheet having the following improvedproperties by being formed into a laminated layer on at least onesurface of a substrate of isotatic propylene resin.

(1) It can be heat-sealed at a considerably lower temperature than thesubstrate.

(2) It has a high heat-seal strength.

(3) It has a good adhesion to the substrate.

(4) It has equal or higher transparency to or than the substrate.

(5) It does not undergo blocking during storage.

(6) It does not stick to bag-making and packing devices.

(7) It has good resistance to scratch.

In the laminated or composite film or sheet described above, theisotactic propylene resin layer as a substrate may be stretcheduniaxially or biaxially. Preferably, the isotactic propylene resin layerof the composite film has a thickness of 5 to 200 microns, morepreferably 10 to 60 microns, and the thickness of the blend of thepropylene/1-butene random copolymer (i) and the isotactic propyleneresin (ii) is 2 to 100 microns, preferably 3 to 30 microns.

The laminated or composite film or sheet can be prepared by variousmethods among which are:

(1) A method which comprises co-extruding and laminating thethermoplastic olefin resin composed of a blend of (i) random copolymerand (ii) isotactic propylene resin and crystalline polypropylene, and ifrequired, stretching the laminate in the longitudinal and transversedirections either simultaneously or at differnt times.

(2) A method which comprises melt-extruding the thermoplastic olefinresin composition on a crystalline polypropylene film as a substrate.

(3) A method which comprises laminating a substrate layer of crystallinepolypropylene film and a film of the thermoplastic olefin resincomposition by an adhesive.

The laminated or composite olefin resin film or sheet in accordance withthis invention has good transparency and excellent low-temperatureheat-sealability. The adhesion between the substrate layer and thelaminated layer of the thermoplastic olefin resin composition is strong,and the laminated film or sheet also has superior scratch resistance andanti-blocking property.

The substrate layer of isotactic propylene resin having a laminatedlayer of the thermoplastic olefin resin composition of this inventionmay be the same polymer as the ingredient (ii) of the olefin resincomposition of this invention. It is especially preferred however to usea substrate layer of isotactic propylene resin having a density of 0.89to 0.92 g/cm³, a melt index (at 230° C.) of 0.1 to 10, and a boilingn-heptane-insoluble content of 75 to 98%.

The thermoplastic olefin resin composition of this invention may containvarious additives used customarily in plastics fabrication. Examples ofsuch additives are heat stabilizers, ultraviolet stabilizers, nucleatingagents, slip agents, antistatic agents, antiblocking agents, antihazeagents, pigments and dyes.

Specific examples include heat stabilizers such as 2,6-ditert-butylp-cresol, tetrakis[methylene(3,5-ditert-butyl-4-hydroxyhydrocinnamate]methane, n-octadecyl-β-(4'-hydroxy-3,5'-ditert-butylphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris(3,5-ditert-butyl4-hydroxybenzyl)benzene, dilauryl thiodipropionate, trisnonylphenylphosphite, 1,1',3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane andα-tocopherol; ultraviolet stabilizers such as2-(2'-hydroxy-3,5'-ditert-butylphenyl)5-chlorobenzotriazole,[2,2'-thiobis-(4-tertiary octylphenolate)] n-butylamine nickel,2-hydroxy-4-n-octoxybenzophenone, nickel dibutyl dithiocarbamate,[bis-(3,5-ditert-butyl 4-hydroxybenzyl monoethyl phosphate)]nickel salt,4-benzoloxy-2,2,6,6-tetramethylpiperidine andbis(2,2,6,6-tetramethyl-4-piperidyl) sebacate; nucleating agents such assilica gel, aluminum hydroxy di-p-tert-butyl benzoate, dibenzylidinesorbitol, aluminum benzoate, talc, sodium adipate and zinc phthalate;slip agents such as oleinamide, erucamide, ethylenebis-oleylamide andethylene-bis-stearylamide; antistatic agents such as stearyldiethanolamine monostearate, lauryl diethanolamine monocaprylate, lauryldiethanolamine and stearyl monoglyceride; antiblocking agents such assilica gel and silica; antihaze agents such as stearyl monoglyceride,propylene glycol monooleate and diglycerin nomooleate; and coloringagents (pigments or dyes) such as titanium white, titanium yellow,yellow iron oxide, zinc ferrite pigment, red iron oxide, ultramarine,cobalt blue, chromium oxide green, chromium titanium yellow, titaniumgreen, phthalocyanine blue, phthalocyanine green, iso-indolinone yellowand quinacridone red.

The amount of these addtives can be chosen properly, and are, forexample, about 0.01 to about 0.5% by weight for the heat stabilizers;about 0.01 to about 0.5% by weight for the ultraviolet stabilizers;about 0.01 to about 0.5% by weight for the nucleating agents; about 0.01to about 1.0% by weight for the slip agents; about 0.01 to about 0.3% byweight for the antistatic agents; about 0.01 about 0.3% by weight forthe antiblocking agents; about 0.1 to about 5.0% by weight for theantihaze agents; and about 0.1 to about 1.0% by weight for the coloringagents, all based on the total weight of the resins (i) and (ii).

In the laminated olefin resin film or sheet in accordance with thisinvention, the substrate layer of isotactic propylene resin may containvarious additives.

Specific examples of these additives include stabilizers such as2,6-di-tert-butyl-p-cresol, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] methane,4,4'-butylidenebis(6-tert-butyl-m-cresol), tocopherols, ascorbic acid,dilauryl thiodipropionate, phosphoric acid-type stabilizing compounds,fatty acid monoglycerides, N,N-(bis-2-hydroxyethyl)alkylamine,2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, andcalcium stearate; ultraviolet absorbers such as 2-hydroxy-4-n-octylbenzophenone, 4-dodecyloxy-2-hydroxybenzophenone,2-(2'-hydroxy-3',5'-ditert-butyl phenyl) benzotriazole,2-(2'-hydroxy-3'-tert-butyl-5'-methyl phenyl) benzotriazole,p-octylphenylsalicylate, carboxyphenyl salicylate, dodecyl salicylate,2-ethyl-hexy-2-cyano-3,3-diphenyl acrylate, resorcinol monobenzoate, and[2,2'-thiobis(4-tert-octyl phenolate)] n-butylamine nickel; antistaticagents such as sorbitan fatty acid monoesters, pentaerythritol fattyacid esters, polyethylene glycol, polyethylene glycol monoethers,polyethylene glycol fatty acid monoesters, betaine derivatives,hydroxyethyl imidazoline sulfuric acid ester, fatty acid salts, sulfuricacid ester salts of higher fatty acid oils and aliphatic amines;lubricants such as liquid paraffin, natural paraffin, microwax,synthetic paraffins, polyethylene wax, stearic acid, lauric acid,stearamide, palmitamide, methylenebis stearmide, ethylenebis stearamide,oleinamide, cetylamide, hardened castor oil, butyl stearate, ethyleneglycol monostearate, cetyl alcohol, stearyl alcohol and metal soaps;pigments such as cadmium orange, red iron oxide, cadmium red, cadmiumyellow, quinacridone red, ultramarine, cobalt blue, phthalocyanine blue,phthalocyanine green, chrome green, aluminum powder, titanium oxide,zinc oxide and carbon black; and organic or inorganic fillers such asmagnesium oxide, magnesium hydroxide, alumina, aluminum hydroxide,silica hydrotalcite, talc, clay, gypsum, glass fibers, titania, calciumcarbonate, carbon black, petroleum resins, polybutene, waxes, andsynthetic or natural rubbers.

The amounts of these additives can be chosen properly, and are, forexample about 0.01 to about 5% by weight for the stabilizers; about 0.01to about 1% by weight for the ultraviolet absorbers; about 0.01 to about10% by weight for the antistatic agents; about 0.05 to about 5% byweight for the lubricants; about 0.05 to about 10% by weight for thepigments; and up to about 150% by weight for the inorganic or organicfillers, all based on the weight of the copolymer or on the total weightof the copolymer and the other resin.

The thermoplastic olefin resin composition of this invention may be inthe form of a blend which is rich in the random copolymer (i) or a blendwhich is rich in the isotactic propylene resin (ii).

The former has improved antiblocking property and mechanical strength inaddition to superior transparency, superior low-temperature heatsealability and good low-temperature shrinkability. Because of theseimproved properties, the resin composition of this type is very usefulas various melt-shaped articles such as shrinkable packaging films orsheets, protecting films or sheets, and textile and general-purposepackaging films or sheets.

The latter type of composition has markedly improved transparency,resistance to whitening by impact and resistance to whitening by bendingin addition to superior thermal stability, superior mechanical strengthand hinge characteristics. Because of these improved properties, thisresin is very useful as various melt-shaped articles, various containerssuch as containers for edible oils and seasonings, containers fortransporting liquids and containers for liquid detergents; blisterpacks, skin packs and similar vacuum-formed packs; tapes having superioroptical characteristics, general-purpose packaging films or sheets,shrinkable packaging films or sheets; injection-molded articles havingsuperior resistance to whitening by impact such as battery cases andtoys; and book covers and files having superior resistance to whiteningby bending.

The method for preparing the thermoplastic olefin resin of thisinvention can be freely chosen, and any means by which the randomcopolymer (i) can be mixed homogeneously with the isotactic propyleneresin (ii) can be used. For example, the ingredients are mixed by aV-type blender, tumbler mixer, Henschel mixer, etc., and then kneaded byan extruder, kneader, mixing rolls, Banbury mixer, etc. It is sufficientthat mixing is performed under conditions which can cause intimatemixing of the random copolymer (i) and the isotactic propylene resin(ii) in the molten state. In mixing or prior to the formation of shapedproducts, additives of the types exemplified hereinabove can beincorporated. Any known melt-shaping means can be used to shape thecomposition of this invention.

The following Examples illustrate the present invention in more detail.Various properties are measured by the following methods.

(1) Tensile characteristics

ASTM-D-882, rate of pulling 50 mm/min.

(2) Degree of haze

ASTM-D-1003

(3) Antiblocking property

ASTM-D-1894

(4) Heat-seal adhesion strength

A film sample is superimposed on itself, and heat-sealed at atemperature of 90, 100, 110, 120, 130, 140, and 150° C. respectivelyunder a pressure of 2 kg/cm² for 1 second using a seal bar width of 5mm, and then allowed to cool. A test piece with a width of 15 mm is cutout from the sample, and the heat-sealed portion is peeled off at across head speed of 200 mm/min. The strength at the time of peeling ismeasured.

(5) Scratch resistance

A bleached kraft paper with an unsized surface is superimposed on theheat-sealed surface of the film. Using an iron block having a weight of500 g as a load, the kraft paper is rubbed once against the film at aspeed of 500 mm/min, and the occurrence of scars is visually evaluated.

(6) Gloss

ASTM-D-2457

(7) Resistance to whitening by bending

A test piece with a size of 6 cm×1.25 cm is bended 180° at its center,and returned to the original state. The presence of whitening isevaluated visually on the following scale.

Good: no whitening is observed.

Fair: slight whitening is observed.

Poor: marked whitening is observed.

(8) Whitening by ball falling

A steel ball weighing 520 g is let fall from a height of 50 cm, and thepresence of whitening is evaluated visually on the following scale.

Good: no whitening is observed.

Fair: slight whitening is observed.

Poor: marked whitening is observed.

(9) Heat distortion temperature

ASTM-D-648

EXAMPLES 1 TO 3 AND COMPARATIVE EXAMPLES 1 TO 3 Preparation of a randomcopolymer (i)

A 20-liter stainless steel polymerization vessel equipped with stirringvanes was charged with 0.01 millimole/liter, as titanium, of a catalystcomponent (a) (which had been prepared by ball-milling 200 g ofanhydrous magnesium chloride, 46 ml of ethyl benzoate and 30 ml ofmethyl polysiloxane in a nitrogen atmosphere, then suspended in titaniumtetrachloride, and filtered), 1.0 millimole/liter, as a concentration inthe polymerization vessel, of (b) triethyl aluminum, and 0.33millimole/liter, as a concentration in the polymerization vessel, ofmethyl p-toluate as an electron donor (c). As a polymerization solvent,n-heptane was fed into the polymerization vessel, and a gaseous mixtureof 68 mole% of propylene and 32 mole% of 1-butene was fed into it at arate of 4 kiloliters/hour and copolymerized at 70° C.

The resulting propylene/1-butene random copolymer had a propylenecontact, as measured by nuclear magnetic resonance spectroscopy, of 71.0mole;, a melting point of 110° C., a heat of fusion of 50 joules/g and amelt index of 7.0.

Preparation of a composition rich in the random copolymer (i)

Pellets of polypropylene (to be referred to as PP) having a melt index,measured at 230° C., of 0.5, a melting point of 165° C., a boilingn-heptane insoluble content of 95% by weight and a density of 0.91 g/cm³and pellets of the resulting propylene/1-butene random copolymer (to beabbreviated as PBC) obtained above were mixed at the mixing ratios shownin Table 1 for 10 minutes using a tumbler blender. The mixture wasformed into a film having a thickness of 30 microns by a 40 mm φ T-dieforming machine while maintaining the temperature of the resin at 230°C.

The film was evaluated, and the results are shown in Table 1.

                                      Table 1                                     __________________________________________________________________________    Examples (Ex.) and Comparative                                                Examples (CEx.)    Ex. 1                                                                              Ex. 2                                                                              Ex. 3                                                                              CEx. 1                                                                             CEx. 2                                                                             CEx. 3                            __________________________________________________________________________    Composition    (i) PBC                                                                           90   75   60   100  97   0                                 (parts by                                                                     weight)       (ii) PP                                                                            10   25   40   0    3    100                               Degree of haze (%) 0.4  0.5  0.5  0.4  0.4  6.8                               Antiblocking property (g/15 mm)                                                                  6.7  5.1  4.3  9.6  9.0  0.1                                               90° C.                                                                    310  90   --   700  500  --                                               100° C.                                                                    530  190  40   840  760  --                                Heat-seal adhesion                                                                           110° C.                                                                    670  710  100  900  800  --                                strength (g/15 mm)                                                                           120° C.                                                                    710  700  220  930  850  --                                               130° C.                                                                    850  820  1060 1010 950  40                                               140° C.                                                                    1010 870  1200 980  1000 80                                               150° C.                                                                    1020 900  1210 1020 1020 290                                     Tensile modulus (kg/cm.sup.2)                                                              3700 4000 4720 3150 3190 11900                                   Stress at yield point                                                   Tensile                                                                             (kg/cm.sup.2)                                                                              135  140  145  126  129  242                               character-                                                                          Tensile strength at                                                     istics                                                                              break (kg/cm.sup.2)                                                                        450  465  471  440  440  495                                     Elongation at break (%)                                                                    600  620  620  610  610  560                               __________________________________________________________________________

EXAMPLES 4 TO 6 AND COMPARATIVE EXAMPLES 4 TO 6

Example 2 was repeated except that a propylene/ethylene random copolymer(to be abbreviated as PEC) having a melt index, measured at 230° C., of7, a melting point of 142° C., a density of 0.91 g/cm³, a boilingn-heptane insoluble content of 30% by weight and an ethylene content of5.5 mole%, or polyethylene (to be abbreviated as PE) having a meltindex, measured at 190° C., of 1.0, a melting point of 131° C. and adensity of 0.955 g/cm³ was used instead of PP.

The results are shown in Table 2.

                                      Table 2                                     __________________________________________________________________________    Examples (Ex.) or Comparative                                                 Examples (CEx.)    Ex. 4                                                                              Ex. 5                                                                              Ex. 6                                                                              CEx. 4                                                                             CEx. 5                                                                             CEx. 6                            __________________________________________________________________________    Composition (parts                                                                          (i)PBC                                                                             90   75   60   97   0    75                                by weight)    (ii) PEC                                                                           10   25   40   3    100  25 (PE)                           Degree of haze (%) 0.4  0.4  0.4  0.4  0.8  8.0                               Antiblocking property (g/15 mm)                                                                  7.1  5.9  4.8  9.4  1.6  5.6                                               90° C.                                                                    450  --   --   630  --   --                                               100° C.                                                                    610  40   --   870  --   --                                               110° C.                                                                    850  200  40   870  --   --                                Heat-seal adhesion                                                                           120° C.                                                                    900  850  800  920  --   70                                strength (g/15 mm)                                                                           130° C.                                                                    950  1010 940  980  490  500                                              140° C.                                                                    1020 1020 1010 1030 1260 1090                                             150° C.                                                                    1100 1100 1150 1160 1370 1300                                    Tensile modulus (kg/cm.sup.2)                                                              3200 3700 4150 3150 7180 7000                                    Stress at yield point                                                   Tensile                                                                             (kg/cm.sup.2)                                                                              131  139  143  129  194  130                               character-                                                                          Tensile strength at                                                     istics                                                                              break (kg/cm.sup.2)                                                                        420  465  471  420  461  440                                     Elongation at break (%)                                                                    610  600  620  620  590  600                               __________________________________________________________________________

EXAMPLES 7 AND 8 AND COMPARATIVE EXAMPLES 7 AND 8

Examples 2 was repeated except that PBC shown in Table 3 which had beenobtained by varying the proportions of propylene and 1-butene was usedinstead of PBC used in Example 2. The results of evaluations are shownin Table 3.

                                      Table 3                                     __________________________________________________________________________    Examples (Ex.) and Comparative                                                Examples (CEx.)      Ex. 7                                                                              Ex. 8                                                                              CEx. 7                                                                             CEx. 8                                    __________________________________________________________________________       Propylene content (mole %)                                                                      60.0 82.0 49.0 93.0                                      PBC                                                                              Heat of fusion (joules/g)                                                                       34   71   20   97                                        Degree of haze (%)   0.4  0.5  1.0  1.0                                       Antiblocking property (kg/cm.sup.2)                                                                5.9  3.8  10.4 1.6                                                        90° C.                                                                     600  --   510  --                                                        100° C.                                                                     720  50   690  --                                                        110° C.                                                                     780  80   700  --                                        Heat-seal adhesion strength                                                   (g/15 mm)       120° C.                                                                     800  1040 790  40                                                        130° C.                                                                     830  1140 800  200                                                       140° C.                                                                     820  1210 810  540                                                       150° C.                                                                     890  1260 800  800                                             Tensile modulus (kg/cm.sup.2)                                                                3050 4610 3000 7250                                      Tensile                                                                             Stress at yield point (kg/cm.sup.2)                                                          130  138  127  193                                       character-                                                                          Tensile strength at break                                               istics                                                                              (kg/cm.sup.2)  425  440  422  484                                             Elongation at break (%)                                                                      610  510  620  540                                       __________________________________________________________________________

EXAMPLES 9 TO 11 AND COMPARATIVE EXAMPLE 9 Preparation of a CompositionRich in the Isotactic Polypropylene (ii)

PP and PBC used in Example 1 were mixed for 10 minutes at the ratiosshown in Table 4 by a tumbler blender and formed into a sheet having athickness of 1 mm by a 40 mm φ T-die forming machine while maintainingthe temperature of the resin at 230° C. The results of evaluating theresulting sheet are shown in Table 4.

                                      Table 4                                     __________________________________________________________________________    Example (Ex.) and Comparative                                                 Example (CEx.)        Ex. 9                                                                             Ex. 10                                                                            Ex. 11                                                                            CEx. 9                                      __________________________________________________________________________    Composition                                                                              (i) PBC     10  20  40  0                                          (parts by weight)                                                                        (ii) PP     90  80  60 100                                              Tensile modulus (kg/cm.sup.2)                                                 Longitudinal     1400                                                                              1100                                                                              830 1640                                             Transverse       1200                                                                              1020                                                                              790 1420                                             Stress at yield point (kg/cm.sup.2)                                           Longitudinal     300 290 250 320                                         Tensile                                                                            Transverse       295 285 250 310                                         charac-                                                                            Tensile strength at break (kg/cm.sup.2)                                  ter- Longitudinal     460 460 460 460                                         istics                                                                             Transverse       450 450 460 450                                              Elongation at break (%)                                                       Longitudinal     500 510 510 460                                              Transverse       510 520 530 500                                         Optical                                                                            Degree of haze (%)                                                                              40  30  23  60                                         prop-                                                                              Gloss (%)         68  73  77  64                                         erties                                                                        Resistance to whitening by bending                                                                  Good                                                                              Good                                                                              Good                                                                              Poor                                        Resistance to whitening by ball falling                                                             Good                                                                              Good                                                                              Good                                                                              Poor                                        Heat distortion temperature (° C.)                                                           125 120 100 130                                         __________________________________________________________________________

EXAMPLES 12 AND 13 AND COMPARATIVE EXAMPLES 10 AND 11

Example 10 was repeated except that PBCs used in Examples 7 and 8 andComparative Examples 7 and 8 were used respectively. The results ofevaluation are shown in Table 5. Table 5 also contains the results ofExample 10 for easy reference.

                                      Table 5                                     __________________________________________________________________________    Example (Ex.) and Comparative                                                 Example (CEx.)        Ex. 12                                                                            Ex. 10                                                                            Ex. 13                                                                            CEx. 10                                                                           CEx. 11                                 __________________________________________________________________________    PBC  Propylene content (mole%)                                                                      60.0                                                                              71.0                                                                              82.0                                                                              49.0                                                                              93.0                                         Heat of fusion (joules/g)                                                                       34  50  71  20  97                                          Tensile modulus (kg/cm.sup.2)                                                 Longitudinal     1030                                                                              1100                                                                              1180                                                                              1030                                                                              1400                                         Transverse       1000                                                                              1020                                                                              1100                                                                              980 1300                                         Stress at yield point (kg/cm.sup.2)                                           Longitudinal     280 290 300 250 300                                     Tensile                                                                            Transverse       280 285 290 250 290                                     character-                                                                         Tensile strength at break (kg/cm.sup.2)                                  istics                                                                             Longitudinal     450 460 470 410 470                                          Transverse       450 450 460 410 470                                          Elongation at break (%)                                                       Longitudinal     500 510 510 520 500                                          Transverse       500 520 530 530 500                                     Optical                                                                            Degree of haze (%)                                                                              25  30  32  27  35                                     prop-                                                                              Gloss (%)         70  73  73  68  70                                     erties                                                                        Resistance to whitening by bending                                                                  Good                                                                              Good                                                                              Good                                                                              Good                                                                              Fair                                    Resistance to whitening by ball falling                                                             Good                                                                              Good                                                                              Fair                                                                              Good                                                                              Poor                                    Heat distortion temperature (°C.)                                                            117 120 122 114 127                                     __________________________________________________________________________

COMPARATIVE EXAMPLES 12 AND 13

Example 10 was repeated except that an ethylene/1-butene randomcopolymer (to be abbreviated as EBC) or an ethylene/propylene randomcopolymer (to be abbreviated as EPC) was used instead of PBC.

EBC had a melt index, measured at 190° C., of 4, an ethylene content of90 mole %, a density of 0.885 g/cm³, a melting point of 79° C. and aheat of fusion of 35 joules/g.

EPC had a melt index, measured at 190° C., of 7.0, an ethylene contentof 80 mole %, and a heat of fusion of less than 5 joules/g.

The results are shown in Table 6. The results of Example 10 are alsoshown in Table 6 for easy reference.

                                      Table 6                                     __________________________________________________________________________    Example (Ex.) and Comparative                                                 Example (CEx.)        Ex. 10                                                                            CEx. 12                                                                           CEx. 13                                         __________________________________________________________________________    Composition                                                                              PP          80  80  80                                             (parts by weight)                                                                        PBC         20 --  --                                                         EBC        --   20 --                                                         EPC        --  --   20                                                  Tensile modulus (kg/cm.sup.2)                                                 Longitudinal     1100                                                                              1070                                                                              1060                                                 Transverse       1020                                                                              980 990                                                  Stress at yield point (kg/cm.sup.2)                                           Longitudinal     290 290 270                                             Tensile                                                                            Transverse       280 270 250                                             character-                                                                         Tensile strength at break (kg/cm.sup.2)                                  ristics                                                                            Longitudinal     470 470 370                                                  Transverse       470 280 270                                                  Elongation at break (%)                                                       Longitudinal     510 510 440                                                  Transverse       530 340 330                                             Optical                                                                            Degree of haze (%)                                                                              30  40  50                                             prop-                                                                         erties                                                                             Gloss (%)         73  69  69                                             Resistance to whitening by bending                                                                  Good                                                                              Poor                                                                              Poor                                            Resistance to whitening by ball falling                                                             Good                                                                              Poor                                                                              Fair                                            Heat distortion temperature (°C.)                                                            120 117 114                                             __________________________________________________________________________

EXAMPLES 14 TO 16 AND COMPARATIVE EXAMPLES 14 AND 15

PBC and PP used in Example 1 were mixed at the mixing ratios shown inTable 7 by means of a tumbling blender for 10 minutes, and granulated bya 40 mmφ extruder at 230° C. The resulting pellets were melted in anextruder, and fed into a die for two-layer films while maintaining thetemperature of the resin at 230° C. Polypropylene having a boilingn-heptane insoluble content of 96% and a melt index of 1.5 was melted ina separate extruder, and fed into the same die while maintaining thetemperature of the resin at 240° C. A composite film was obtained inwhich the thickness of the polypropylene substrate layer was 40 microns,and the thickness of the heat sealed layer was 10 microns.

The results of evaluations are shown in Table 7.

                                      Table 7                                     __________________________________________________________________________    Example (Ex.) and Comparative                                                 Example (CEx.)    Ex. 14                                                                            Ex. 15                                                                            Ex. 16                                                                            CEx. 14                                                                           CEx. 15                                     __________________________________________________________________________    Composition                                                                              PBC     90  75  60 100  0                                          (parts by weight)                                                                        PP      10  25  40  0  100                                         Degree of haze (%)                                                                              3.8 4.0 4.0 3.8 6.8                                         Antiblocking property (g/15mm)                                                                  7.8 6.2 4.3 1.9 0.1                                         Scratch resistance                                                                              Good                                                                              Good                                                                              Good                                                                              Fair                                                                              Good                                                    90° C.                                                                       580 180 --  760 --                                                     100° C.                                                                       790 420  70 770 --                                          Heat-seal adhesion                                                                       110° C.                                                                       820 770 220 760 --                                          strength (g/15 mm)                                                                       120° C.                                                                       850 860 500 800 --                                                     130° C.                                                                       840 910 810 810 110                                                    140° C.                                                                       890 880 920 760 290                                                    150° C.                                                                       870 900 940 750 750                                         __________________________________________________________________________

EXAMPLES 17 TO 19 AND COMPARATIVE EXAMPLE 16

The procedure of Examples 15 and 16 was repeated except that apropylene/1-butene random copolymer (to be referred to as PBC-2)obtained by varying the mixing ratio of a propylene/1-butene gaseousmixture and having a propylene content of 80.3 mole %, a melting pointof 124° C., a heat of fusion of 68 joules/g and a melt index of 7.0 wasused instead of PBC. The results are shown in Table 8.

                                      Table 8                                     __________________________________________________________________________    Example (Ex.) and Comparative                                                 Example (CEx.)    Ex. 17                                                                             Ex. 18                                                                             Ex. 19                                                                             CEx. 16                                      __________________________________________________________________________    Composition                                                                              PBC-2   90   75   60   100                                         (parts by weight)                                                                        PP      10   25   40    0                                          Degree of haze (%)                                                                              3.6  3.7  3.9  3.4                                          Antiblocking property (g/15 mm)                                                                 3.0  2.2  1.5  3.9                                          Scratch resistance                                                                              Excellent                                                                          Excellent                                                                          Excellent                                                                          Good                                                     90° C.                                                                        50  --   --    130                                                    100° C.                                                                        280  60  --    380                                         Heat-seal adhesion                                                                       110° C.                                                                        720  210  50   820                                         strength (g/15 mm)                                                                       120° C.                                                                       1020  740  180 1060                                                    130° C.                                                                       1130 1050  460 1170                                                    140° C.                                                                       1170 1180 1010 1200                                                    150° C.                                                                       1280 1250 1200 1240                                         __________________________________________________________________________

What we claim is:
 1. A laminated olefin resin film or sheet comprising asubstrate of an isotactic propylene resin and formed on at least onesurface thereof, a laminated layer of a thermoplastic olefin resincomposition, said composition being composed of a blend of(i) 50 to 95%by weight, based on the total weight of the blend, of a random copolymerconsisting essentially of 55 to 85 mole % of propylene and 45 to 15 mole% of 1-butene and having a heat of fusion of 10 to 80 joules/gdetermined by differential thermal analysis using a differentialscanning calorimeter, and (ii) 5 to 50% by weight, based on the totalweight of the blend, of an isotactic propylene resin containing 0 to 10mole % of another α-olefin and having a melting point of 135° to 165° C.and a melt index, measured at 230° C., of 0.1 to
 20. 2. The film orsheet of claim 1 wherein the substrate is a biaxially stretchedsubstrate.
 3. The laminated olefin resin composition of claim 1, whereinthe random copolymer has a melt index of 0.1 to
 40. 4. The laminatedolefin resin composition of claim 1, wherein the random copolymer has apropylene content of 60 to 82 mole %.
 5. The laminated olefin resincomposition of claim 1, wherein the random copolymer has a heat offusion of 20 to 70 joules/g.